1. Field of the Invention
The present invention relates to a recording disk drive such as a hard disk drive (HDD), and in particular, to a recording disk drive comprising a recording disk and a shroud wall spaced from the peripheral end of the recording disk.
2. Description of the Prior Art
It is well known in the field of HDDs that turbulence within the enclosure of the magnetic recording disk causes a flutter of the rotating magnetic recording disk. Such turbulence is usually induced by the rotation of the magnetic recording disk. For example, Japanese Patent Laid-open No. 53-57009 discloses an annular plate surrounding the magnetic recording disk so as to reduce the flutter. The disclosed technique suggests that the outer periphery of the magnetic recording disk is spaced apart from the inner wall of the annular plate by 1.0 mm. Reduction of the flutter is in general required to avoid collision of the flying head slider against the surface of the rotating magnetic recording disk in the HDD.
The magnetic recording disk has got smaller in size. Reduction in size of the magnetic recording disk is accompanied with reduction in the amplitude of the flutter. In addition, the behavior of the flying head slider has got a higher stability, which serves to avoid variation in the flying height of the flying head slider above the surface of the magnetic recording disk. Accordingly, less probability can be found in collision of the flying head slider against the magnetic recording disk in the HDD in recent years.
There is still a greater demand for. a higher storage density to a magnetic recording disk. The storage density can be improved by reducing spaces between the adjacent recording or data tracks on the magnetic recording disk. Reduction in spaces between the data tracks cannot be considered without taking flutter of the rotating magnetic recording disk into account. Flutter induces sway of the magnetic recording disk at the outer periphery in the direction orthogonal to the surface of the disk, namely, the longitudinal direction. Such sway induces not only the collision of the flying head slider against the magnetic recording disk but also the lateral shift of the data tracks which leads to failure in positioning the flying head slider above the target data track. Specifically, the flutter of the rotating magnetic recording disk is a factor to obstruct reduction in spaces between the adjacent data tracks. Heretofore, no consideration has been made on appropriate conditions for effectively reducing the flutter of a smaller magnetic recording disk such as a 3.5 inches or 2.5 inches magnetic disk in an HDD.
It is accordingly an object of the present invention to provide a recording disk drive comprising a shroud wall capable of effectively reducing the flutter of a recording disk.
According to a first aspect of the present invention, there is provided a recording disk drive comprising: a recording disk; a shroud wall spaced from an peripheral end of the recording disk by a gap equal to or smaller than 0.5 mm; and a rectification groove formed in the shroud wall at a position adjacent an area opposed to the peripheral end of the recording disk.
The present inventors have found out that reduction in gap between the peripheral end of the recording disk and the shroud wall serves to reduce the amplitude of the flutter to be induced in the rotating recording disk. Moreover, as the gap gets smaller, the flutter reduces at a higher rate in response to increase of the depth of the rectification groove. Specifically, if the gap between the peripheral end of the recording disk and the shroud wall is set equal to or smaller than 0.5 mm, the groove can be made shallower so as to still efficiently suppress the flutter of the rotating recording disk.
The rectification groove preferably has a depth equal to or smaller than 2 mm. The present inventors have found from their unique observation that a rectification groove of a depth larger than 2 mm hardly serves to reduce the flutter of the rotating recording disk.
The recording disk drive may further comprise an enclosure enclosing the recording disk, and a shroud member inserted into the enclosure to define the shroud wall with the rectification groove. According to the arrangement, it is unnecessary to form the rectification groove directly on the enclosure, so that the process of producing the recording disk drive may be simplified.
According to a second aspect of the present invention, there is provided a recording disk drive comprising: a recording disk; an enclosure enclosing the recording disk; a shroud member inserted into the enclosure so as to keep a gap equal to or smaller than 0.5 mm to an peripheral end of the recording disk; and a rectification groove formed in the shroud member at a position adjacent an area opposed to the peripheral end of the recording disk.
A recording disk drive of the second aspect may achieve the aforementioned advantages in the same manner as the first aspect. In addition, the shroud member employed in the second aspect may serve to facilitate the process of producing the recording disk drive.
Furthermore, a method of assembling the aforementioned recording disk drive, may comprise: preparing an enclosure of a recording disk; forming a groove on an inner surface of a tubular material having an inside diameter larger than an outside diameter of the recording disk, the groove extending in a circumferential direction of the tubular material; cutting an annular member off the tubular material, the annular member including the groove formed on its inner surface; and setting the annular member in the enclosure so as to oppose the inner surface of the annular member to a peripheral end of the recording disk by a predetermined gap. The peripheral end of the recording disk is opposed to the inner surface at an area adjacent the groove.
It should be noted that the present invention may be applied not only to a magnetic recording disk drive such as a hard disk drive, for example, but also to an optical recording disk drive employing an optical recording disk such as a compact disk (CD, CD-R, CD-RW) and a digital video disk (DVD), as well as a magneto-optical disk drive employing a magneto-optical disk (MO).